At that time, the advertising manager had an interesting idea on how to do a survey to determine the relative popularity of the AM radio station in the local market. His idea, which he likely read in one of his trade publications, was to see what stations were tuned-in on the radios of parkedcars around the city. This was easy, since there were just four radio stations at the time. Today, that type of survey couldn't be done for two principal reasons. First, people would wonder about people peering into every parkedautomobile on a street; and, second, modern radios show no indication of what station was tuned when the automobile is off.

In those days, however, radios were mechanically-tuned with a knob that also moved a frequency indicator along a slide display (see photo). Since the FCC assigns station frequencies at intervals to prevent interference between stations, it was easy to see from this indicator which of the four stations (950, 1250, 1310, and 1550 kHz) was last heard. Later, car radios were designed to receive both AM and FM radio stations, the tuning dial was used for both, and it would have been hard to determine whether an AM or an FM station was last tuned; but, this survey method was workable at that time. Our station ranked first in this survey.

Wireless technologies, such as RFID, have enabled very efficient inventory control. This is, in effect, a survey of goods, but other wireless devices enable surveys when that's not their intended purpose. One controversial method of traffic survey is through use of the now ubiquitous E-Zpass system that's intended for electronic toll collection. Since E-Zpass RFID tags can be detected at non-toll locations, they're also used to provide estimates of travel time between points. While it's claimed that these data are scanned in an encrypted form and deleted as soon as the travel time estimate has been completed, people are still concerned about later "enhancements" to these systems.

The usual census-taking method, at least in the US, involves mailedquestionnaires, and home visits to those who don't respond. All this could be done more quickly, although with less accuracy at first, using cellphone data. However, in the extended period between traditional census-taking, it would offer better accuracy. The international research team, led by geographer, Catherine Linard, of the Université Libre de Bruxelles and data scientist, Pierre Deville, of the Université Catholique de Louvain used cellphone data as a way to estimate the population density of France and Portugal.[3] They used a dataset of more than a billion call records from these countries.[2]

In the case of Portugal, the call records were for two million users, which is about 20% of the population. For France, the records were for seventeen million users, which is about 30% of the population. Call records for Portugal included the cellphone identifier code, the locations of the originating and receiving cellphone towers, and the start and stop times of the call. The data for France were limited to just the day of the call and the tower locations.[3] Corrections were made to allow for the fact that cell towers are not uniformly distributed.

Possibly the most important application of such cellphone data is the ability to track population flow in emergencies to allow for adequate impact assessments and intervention planning.[2] As the authors write in their article,

"...The prospect of being able to map contemporary and changing human population distributions over relatively short intervals exists, paving the way for new applications and a near real-time understanding of patterns and processes in human geography."[2]